In the swashplate axial piston pump model established by AMESim, the controlled throttle valve was usually used to simulate the flow rate change between the cylinder waist type window and the plate window during the distribution process. The actual control curve of the throttle valve depends on the geometric size of the distribution window, which has a certain influence on the flow pulsation of the simulation results. The curve of the flow area of the distribution mechanism was derived, which was beneficial to the theoretical research of the pump simulation model and the optimization of the pump distribution structure.